Applicant claims priority from French patent application 0206473 filed May 28, 2002.
A smart card, which may have about the same dimensions as a credit card, has one or more embedded integrated circuits, and has an active face with a plurality of contact pads that connect to the integrated circuit. A common arrangement includes six pads arranged in three columns and two rows. An electrical connector for connecting read/write circuitry to the card may include an insulative base with a card-receiving upper face, and with the contacts having pad-engaging ends projecting above the upper face, to be depressed by the pads of the smart card.
A card may be installed on the base in a number of ways, as by sliding it along the upper face or mounting it on a cover that pivots down the card until it lies facewise adjacent to the base upper face. Many card connectors include an electrical switch for detecting the presence of a card as it approaches the fully inserted position. Such a switch can make or break a switching circuit.
A switching circuit for detecting a smart card approaching a fully inserted position, can include a sheet metal switch blade that is depressed by the card so the blade engages another contact. Some problems that can arise with such a switch are that the card may become scratched by the portion of a sheet metal blade that the card engages, since the card is usually of plastic at its outside surface except at its metal contact pads. Also, there is a risk that the switch blade will engage one of the card contact pads and possibly pass a damaging current to it. A switch with a pair of switch contacts, wherein one of the switch contacts engages a card to detect the card approaching a full insertion position, which avoided the above disadvantages, would be of value.
In accordance with one embodiment of the present invention, a smart card connector is provided, with an electrical switch that detects a smart card close to its fully inserted position, while avoiding scratching of the card or the inadvertent connection of unwanted currents to contact pads of the card. The connector is of the type that includes an insulative base with an upper card-receiving surface and contacts with pad-engaging portions projecting above the surface to engage pads of a smart card that lies facewise adjacent to the base card-engaging surface. A switch for detecting a card near its fully installed position includes first and second switch contacts mounted on the base. The second switch contact includes a sheet metal switch blade that can be depressed by a card so the switch blade moves against the first contact or moves out of engagement with the first contact. A depressable element of insulating material is mounted on the blade, the depressable element having a top lying above the blade. As a result, a card near the fully installed position engages only the top of the depressable element to depress the contacting part of the second switch contact.
The depressable element is preferably formed of a polymer and has a rounded top, the polymer having a hardness no more than one fifth that of the metal of the switch blade. As a result, the depressing element, which is the only part engaged by a card, is unlikely to scratch the card, and cannot conduct electricity to a contact pad that happens to engage the element.
The switch blade has a blade hole, and the depressable element is trapped to walls of the blade hole by lying closely above and below the walls of the blade hole. This can be accomplished by projecting a stub upward through the blade hole and deforming the top of the stub to trap it to the blade while forming a rounded top on the stub.
The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when used in conjunction with the accompanying drawings.